* * * * *
In the majority of Ganoids the division of the segmental duct of the kidney into two would seem to occur, and the ventral duct of the two (Müllerian duct), which opens at its upper end into the body-cavity, is said to serve as an excretory duct for both male and female organs.
The following are the more important facts which are known about the generative and urinary ducts of Ganoids.
In Spatularia (vide Hyrtl, Geschlechts u. Harnwerkzeuge bei den Ganoiden, Denkschriften der k. Akad. Wien, Vol. VIII.) the following parts are found in the female.
(1) The ovaries stretching along the whole length of the abdominal cavity.
(2) The kidneys, which are separate and also extend along the greater part of the abdominal cavity.
(3) The ureters lying on the outer borders of the kidneys. Each ureter dilates at its lower end into an elongated wide tube, which continues to receive the ducts from the kidneys. The two ureters unite before terminating and open behind the anus.
(4) The two oviducts (Müllerian ducts). These open widely into the abdominal cavity, at about two-thirds of the distance from the anterior extremity of the body-cavity. Each opens by a narrow pore into the dilated ureter of its side.
In the male the same parts are found as in the female, but Hyrtl found that the Müllerian duct of the left side at its entrance into the ureter became split into two horns, one of which ended blindly. On the right side the opening of the Müllerian duct was normal.
In the Sturgeon (vide J. Müller, Bau u. Grenzen d. Ganoiden, Berlin Akad. 1844; Leydig, Fischen u. Reptilien, and Hyrtl, Ganoiden) the same parts are found as in Spatularia.